With development of mobile communications, more and more attention has been paid to positioning technology of mobile phones. As limitation exists in both GPS (Global Positioning System) positioning and other positioning manners using wireless sensor network or the like, a future direction of improvement lies in integrated positioning (multimode positioning) through cooperation of multiple positioning systems so as to achieve a better accuracy of positioning. In this way, advantages of various positioning systems can be exploited, such that a better accuracy and a quick response as well as a relatively broad cover range can be enabled to realize ubiquitous and accurate positioning. For example, the GPS may be combined with the mobile communication system for positioning of a mobile phone. When the GPS is in use, it is required to search out at least four satellites before completion of positioning by solving equations. In indoor condition at crowd urban area, however, the requirement of searching out four satellites may be not satisfied due to serious attenuation of GPS signal, such that GPS positioning cannot be performed and the positioning function may be restricted.
In view of above, a pseudolite solution based on navigation satellites has been proposed to improve indoor positioning. Such solution is implemented by setting pseudolites similar to navigation satellites, which are able to transmit same signal as that of the navigation satellites, at low altitude. As the pseudolites are close to ground, it is possible to achieve a great strength of signal and low attenuation, such that indoor coverage of signal can be extended efficiently. But on the other hand of the solution, it is required for a receiver to process signal dynamic range for both the navigation satellites and the pseudolites as well as to overcome signal interference therebetween, and an additional wireless system is required.